some time ago it was very popular doing courier scams where the docking rights are revoked after a hauler capsuler accepte a public contract. Then CCP did the great Cargo Deposit feature which makes it possible to deliver a package, even without docking rights.
Now with Quantom Cores some scammers abusing the game mechanic in one more or less legit way. They put the Citadel (mostly Raitaru is used) into “onlining” mode and the Cargo Deposit wont work in that mode.
Also long term capsulers are not aware that in that in “onlining” mode they cant use Cargo Deposit and accept contracts. They not aware cause CCP promoted that feature in the past but never did a update after Quantum Cores on that.
Quick Fix: The official documentation related to courier contract should be extended about the information that couriers cant be delivered if destination citadel is in that mode.
Game change proposal: In “onlining” mode you can dock right now. So Cargo Deposit should work too in that mode to make that abusing of game mechanic no longer possible.